ANAT2111 Introductory Anatomy Lecture 4 Articular System Structural Classes of Joints Based on the type of substance between articulating bones: Fibrous joints - least mobile Cartilaginous joints Synovial joints - most mobile
Fibrous Joints At a fibrous joint the bones are held together by dense connective tissue. (a) Suture Joint held together with very short, interconnecting fibers, and bone edges interlock. Found only in the skull. (b) Syndesmosis Joint held together by a. Fibrous tissue can vary in length but is longer than in sutures. (c) Gomphosis Peg-in-socket fibrous joint. Periodontal holds tooth in socket. Suture line Fibula Tibia Socket of alveolar process Root of tooth Dense fibrous connective tissue Ligament Periodontal Skull Sutures Coronal suture Parietal bone Squamous suture Lambdoid suture Frontal bone Sphenoid bone (greater wing) Ethmoid bone Lacrimal bone Lacrimal fossa Occipital bone Temporal bone Zygomatic process Occipitomastoid suture Nasal bone Zygomatic bone Maxilla External acoustic meatus Mastoid process Styloid process Mandibular condyle Mandibular notch Mandibular ramus Alveolar margins Mandible Mental foramen Mandibular angle Coronoid process
Skull Sutures Posterior fontanelle Parietal bone Ossification center Frontal bone Sphenoidal fontanelle Temporal bone (squamous portion) Mastoid fontanelle Occipital bone Frontal suture Frontal bone Anterior fontanelle Ossification center Parietal bone Posterior fontanelle Occipital bone Cartilagenous Joints At a cartilagenous joint bones are held together by cartilage (a) Synchondroses (Primary cartilaginous joint) Bones united by hyaline cartilage Sternum (manubrium) Epiphyseal plate (temporary hyaline cartilage joint) Joint between first rib & sternum (immovable)
Cartilagenous Joints At a cartilagenous joint bones are held together by cartilage (b) Symphyses (Fibrocartilaginous joint) Bones united by fibrocartilage Body of vertebra Fibrocartilaginous intervertebral disc Hyaline cartilage Pubic symphysis Intervertebral Discs Structure of the annulus fibrosus
Intervertebral Discs Herniation or slipping of the intervertebral disc Vertebral spinous process Spinal cord Spinal nerve root Transverse process Herniated portion of disc Nucleus pulposus of disc Anulus fibrosus of disc Characteristic Features: Joint (synovial) cavity Synovial Joints Hyaline (articular) cartilage Fibrous capsule Synovial membrane Ligaments Ligament Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Fibrous capsule Synovial membrane Periosteum Articular capsule
Ligaments Prohibit movements in undesirable directions Limit the range of normal movements May exist to protect or hold some important structure in position Acromion Coracoacromial Subacromial bursa Coracohumeral Coracoid process Articular capsule reinforced by glenohumeral s Greater tubercle of humerus Transverse humeral Tendon sheath Subscapular bursa Tendon of the subscapularis muscle Scapula Tendon of long head of biceps brachii muscle Types of Synovial Joints Uniaxial - plane, hinge, pivot Biaxial ellipsoid/condyloid Multiaxial - ball & socket
Uniaxial Joints Metacarpals Carpals Plane joint (Intercarpal joints) Gliding Humerus Medial/ lateral axis Ulna Hinge joint (Elbow joint) Flexion and extension Uniaxial Joints Vertical axis Ulna Radius Pivot joint (Proximal radioulnar joint) Rotation
Biaxial Joints Phalanges Biaxial movement Medial/ lateral axis Anterior/ posterior axis Metacarpals Condyloid joint (2nd-5th Metacarpophalangeal joints) Flexion and extension Adduction and abduction Multiaxial Joints Multiaxial movement Scapula Medial/lateral axis Anterior/posterior axis Vertical axis Humerus Flexion and extension Ball-and-socket joint (Glenohumeral joint) Adduction and abduction Rotation
Factors Stabilising Joints Shape of articulating surfaces (important in hip joint) Ligaments (important in intervertebral joints & ankle joint) Muscles (important in shoulder joint) Glenohumeral (Shoulder) Joint Articular surfaces of the shoulder joint Note: The shallowness of the socket (glenoid cavity) The glenoid labrum increases the articular surface area for the head of the humerus Acromion Coracoacrominal lig. Coracoid process Fibrous articular capsule Glenoid cavity Glenoid labrum Tendon of long head of biceps brachii muscle Glenohumeral s Tendon of the subscapularis muscle Scapula Posterior Anterior
Shoulder Joint: Synovial fluid Acromion of scapula Coracoacromial Subacromial bursa Fibrous articular capsule Tendon sheath Glenoid labrum Synovial cavity of the glenoid cavity containing synovial fluid Hyaline cartilage Tendon of long head of biceps brachii muscle Synovial membrane Fibrous capsule Humerus Shoulder Joint: Ligaments Acromion Coracoacromial Coracoid process Subacromial bursa Coracohumeral Fibrous articular capsule reinforced by Glenohumeral s Greater tubercle of humerus Transverse humeral Tendon sheath Subscapular bursa Tendon of the subscapularis muscle Scapula Tendon of long head of biceps brachii muscle Note: Shoulder Joint Capsule & Coracoacromial arch (formed by the coracoid process, acromion & coracoacromial lig.)
Shoulder Joint: Muscles Note humerus removed The capsule is reinforced on three sides by muscles (known collectively as the rotator cuff). The shoulder joint relies primarily on the rotator cuff muscles for its stability. Shoulder: X-Ray & Dislocation Anterior dislocation of head of humerus Elsevier Ltd. Drake et al: Gray s Anatomy for Students www.studenconsult.com
Hip Joint Articular cartilage Acetabular labrum Femur Coxal (hip) bone Ligament of the head of the femur (um teres) Synovial cavity Articular capsule Hip Joint: Dissection Acetabular labrum Synovial membrane Ligament of the head of the femur (um teres) Head of femur Articular capsule (cut)
Hip Joint: Capsule & Ligaments Iliofemoral Ischium Ischiofemoral Greater trochanter of femur Hip Joint: Capsule & Ligaments Anterior inferior iliac spine Iliofemoral Greater trochanter Pubofemoral
Knee Joint Articular surfaces - medial & lateral condyles of femur and tibia and the patella Relies on s & muscles for stability Tendon of quadriceps femoris Femur Articular capsule Posterior cruciate Lateral meniscus Anterior cruciate Tibia Suprapatellar bursa Patella Subcutaneous prepatellar bursa Synovial cavity Lateral meniscus Infrapatellar fat pad Deep infrapatellar bursa Patellar Knee Joint: Menisci & Capsule The Menisci act to: deepen the contour of the tibia plateau thereby increasing the area of femoral contact & evening the distribution of compressive load. stabilise the joint by guiding the femoral condyles during flexion/extension & preventing side-to-side rocking of the femur on the tibia. Anterior cruciate Anterior Articular cartilage on medial tibial condyle Articular cartilage on lateral tibial condyle Medial meniscus Posterior cruciate Lateral meniscus
Knee Joint: Capsule & Ligs. Quadriceps femoris muscle Tendon of quadriceps femoris muscle Patella Tendon of adductor magnus Medial head of gastrocnemius muscle Femur Articular capsule Oblique popliteal Fibular collateral Patellar Fibula Tibia Tibial collateral Popliteus muscle Tibial collateral Tendon of semimembranosus muscle Lateral head of gastrocnemius muscle Bursa Fibular collateral Arcuate popliteal Tibia Knee Joint: Ligaments Fibular collateral Lateral condyle of femur Lateral meniscus Tibia Fibula Posterior cruciate Medial condyle Tibial collateral Anterior cruciate Medial meniscus Patellar Patella Quadriceps tendon The Collateral ligs. act to: stabilise the knee joint & prevent sideto-side (abduction/adduction) rocking of the femur on the tibia. prevent hyperextension of the knee joint by tightening during extension. The Cruciate ligs. act to: stabilise the knee joint & prevent hyperextension by tightening during extension. prevent posterior sheering of femur relative to tibia (anterior cruciate) or posterior sheering of tibia relative to femur (posterior cruciate).
Knee Joint: Cruciate Ligs. 1 During movement of the knee the anterior 2 When the knee is fully extended, both cruciate prevents anterior sliding of the tibia; cruciate s are taut locking the the posterior cruciate prevents posterior knee and preventing hyperextension. sliding of the tibia. Quadriceps muscle Femur Patella Medial condyle Anterior cruciate Anterior cruciate Lateral meniscus Posterior cruciate Tibia Posterior cruciate Knee Joint: Injury Lateral Medial Patella (outline) Lateral force Tibial collateral (torn) Medial meniscus (torn) Anterior cruciate (torn) Anterior view
Knee Joint: Osteoarthritis